Samsung Galaxy Z Fold 3 durability: Did the phone stand up to 18 hours of S Pen use?

It's unlikely anyone would draw on a phone for as long as we did, but it was a fun experiment -- with interesting results.

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Chris Parker
5 min read

We put together an extreme drawing experiment, having an S Pen draw on the Galaxy Z Fold 3 for what turned out to be a little more than 18 hours. This isn't how anyone would use their S Pen, but we wanted to give it a try.

Chris Parker/CNET

CNET doesn't shy away from testing durability claims, sometimes pushing the boundaries of how one would ever use their phone. These include drop tests from high heights. Or water tests in places where you likely wouldn't bring your phone. When the new foldable phones started coming on the market from Motorola and Samsung , we even did folding tests, folding a phone more times in a row than you ever would.

Even before the latest Samsung foldables were announced, I'd been trying to figure out a new kind of experiment to gauge the resilience of these phones . Could we test the strength of the hinges with weights? Maybe use it as a shovel at the beach to see if any sand got inside?

With the introduction of the Galaxy Z Fold 3 and its accompanying S Pen Fold Edition, I decided we should look at the durability of the screen itself. I was curious to find out how much one could draw on the screen with the S Pen before any ill effects could be noticed. 

I knew randomly drawing on the screen for an extended period of time was no way to conduct the experiment, so I turned to my 3D printer, which I knew was capable of generating consistent repetitive motions. I modified my Creality Ender 3 V2 printer to make it a plotter instead and printed out a holder to make it work with the S Pen.

Then, with a little help from the internet, I had to teach myself how to program a little bit of g-code so I could make the plotter do what I needed it to. The key ended up being this little string right here: G2 F5277 I50 J0. With some trial and error, I figured out this bit of code would draw a circle with a radius of 50 millimeters 1,000 times in one hour. Copy and paste 1,000 times in Notepad and voila!

The Galaxy Z Fold 3 looks slick with its new design

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Finally, once I got the Z Fold 3 in hand, I had to find a good drawing program that would be interesting to watch for 16 hours. I landed on Infinite Painter because of its clean interface and huge supply of interesting brushes. Clearly we're looking at an extreme drawing marathon that would push the boundaries of both the phone's screen and the S Pen itself, well beyond the occasional use that would be more realistic.

And if you're curious, here's some of the math behind my madness:

  • Radius of circle being drawn: 50 mm
  • Circumference of circle: 314.16 mm
  • The machine draws 1,000 circles in 1 hour
  • 1,000 circles x 314.16 mm = 314,160 mm/hr = 314.16 meters per hour
  • 5 kilometers would take 15.9 or basically 16 hours
  • 314.16 meters per hour = 1,030.7 feet per hour
  • 1 mile = 5.12 hours
  • 3 miles would take 15.36 hours
  • 5 kilometers = 3.1 miles

The S Pen took a beating from our extreme drawing experiment.

Chris Parker/CNET


Our 16-hour experiment ended up running a little over 18 hours, but after 16,000 circles drawn on the surface of the Z Fold 3, there is no visual or tactile indication that any kind of damage to the screen occurred. The S Pen wasn't so lucky.

Given the setup of my 3D printer, it was hard to gauge what was going on with the tip of the S Pen while it was locked in the machine. I had to wait until the test was over to remove the S Pen from its holder, and when I did, it was apparent that the very end of the tip was breaking off, like a tiny ball of loose plastic. 

When placed side by side with a fresh S Pen, it was clear the one used in the machine was no longer in mint condition. Luckily, Samsung provides three replacement tips with the Pen, plus a little tool to remove the used one. It's almost as if Samsung knew something like this could happen.

Back to the phone, I was really pleasantly surprised how well the screen held up during the experiment. There were a few little snags that came up through the night though.

The first one we ran into was when the drawing app I was using, Infinite Painter, crashed three separate times. My guess is that the complexity of the drawing in those instances became too much for the app to handle, so it bailed out. I'm no software engineer though, so don't quote me on that, but each time it happened, the phone returned to the home screen and the plotter kept drawing making the same circular motion. There was just nothing being drawn.

The Galaxy Z Fold 3 looks slick with its new design

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For those curious about the battery life of the Z Fold 3, the battery lasted just over six hours before it ran out the first time. That seemed pretty good to me after keeping the screen on the whole time and registering that the S Pen was drawing on it.

I plugged the phone in to charge it (while continuing with the experiment) and once it was fully recharged again, the battery lasted close to six hours again. I decided to plug the phone in before the battery was fully drained, since I wanted to finish out the 16,000 circles with an image to look at, and not a boring black screen.

The last thing of note was the temperature of the phone. Most of the time, when I lifted the phone from the machine, the temperature seemed normal. But a handful of times when I picked it up, the phone was quite hot, on both the screen side and on the back.

Again, I don't have a specific cause for the change in temperature, but my assumption is that it could have been the complexity of the drawing, the brightness of the screen as the drawing evolved or perhaps something related to having it plugged in during charging. Regardless, each time I noticed it was warm, it cooled off rather quickly, and I never saw any overheating warnings.

Given all of that, I'd say the Galaxy Z Fold 3 was a real trooper throughout the experiment, and the S Pen will live to see another day. Once I replace that tip.